This invention relates generally to marine propulsion devices, such as outboard motors, and, more particularly, to a drive shaft assembly for use in such a marine propulsion device.
Drive shafts in conventional outboard motors are typically provided with one or more bearing races adjacent their lower ends and are exposed to corrosive water and exhaust gases at their upper ends. To provide improved lower end wear characteristics in conjunction with improved upper end corrosion resistance, prior drive shafts have been manufactured by friction welding a lower drive shaft member of carbon steel to an upper drive shaft member of stainless steel. However, friction welding is disadvantageous in that it requires costly secondary operations such as machining, heat treating and straightening. Further, if either of the upper or lower drive shaft require servicing, the entire drive shaft must be removed.
Attention is directed to the following U.S. Pat. Nos.:
______________________________________ Culver 687,676 November 26, 1901 Peck 1,843,089 January 26, 1932 Bossen 2,384,436 September 11, 1945 Graue 2,466,097 April 5, 1949 Kiekhaefer 2,549,484 April 17, 1951 Green 2,587,838 March 4, 1952 Hansson et al. 3,006,311 October 31, 1961 Crum, Jr. 3,069,875 December 25, 1962 Walden 3,212,290 October 19, 1965 Ackerman 3,256,851 June 21, 1966 Wynne 3,376,842 April 9, 1968 Croisant 3,931,783 January 13, 1976 Federmann et al. 4,421,497 December 20, 1983 Karrasch et al. 4,792,315 December 20, 1988 ______________________________________